<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
    var arr = [1,2,3,4,5,6,7,8,9];
    // console.log(arr.length);
    // 清空数据 数组长度为0；
    // arr.length = 0;
    // console.log(arr);

    // 清空数组的数据  让数组的数据为空
        // arr = [];
        // console.log(arr);

    // 清空数组的数据 splice(start,end)
       arr.splice(0,arr.length);
       console.log(arr);


    </script>
</body>
</html>